If by 'Import' you mean 'display an arbitrary image file from disk', you can set an unbound object control's SourceDoc proprerty from VB, like
MyOLEControl.Class= "Imaging.Document"
MyOLEControl.SourceDoc="path\filename.jpg"
As for thumbnails & enlarging, it's been my experience that a small control with
.SizeMode = acOLESizeZoom
is a fine approximation for a thumbnail, and if this smaller control's SourceDoc is assigned to a larger control otherwise configured as above, there's your zoom. Or somthing like that.